Vertical lift doors have long been in use in both commercial and residential garages as well as in industrial facilities such as warehouses, factories, and the like. Increasingly, vertical lift doors are being incorporated into consumer-directed, commercial buildings such as restaurants and retail establishments, so as to permit these buildings, under appropriate conditions, to be opened to the ambient atmosphere.
In a typical vertical lift door system, a door is moved from a closed position to an open, storage position. In most instances, the door is comprised of a single, unitary body which is moved from a vertical, closed position along a series of tracks or guides to a horizontal storage position, typically under the ceiling of the building structure. The horizontal storage of the large door panel consumes a large amount of useful ceiling space in the building structure, which space could otherwise be utilized productively. Also, in those instances where vertical lift doors are associated with consumer-oriented applications such as retail or restaurants, the presence of an overhead door can be unsightly. In addition to these problems, the horizontal storage imposes mechanical forces on the door which can tend to warp the door unless reinforcing members are included. As a consequence of these limitations, the art has looked to alternative vertical door structures.
One such alternative comprises roll-up doors which include a corrugated, flexible door structure which is wound into an overhead storage drum. While these doors can be quite sturdy, their high weight, mechanical complexity, and high cost tend to restrict their utility to heavy duty commercial applications. In addition, the appearance of such doors generally limits their use in residential and consumer oriented applications.
Other vertical door systems include accordion folded door members comprised of a plurality of interconnected panels which are variously conveyed from a closed configuration to an open, storage configuration. The interconnected nature of the panels makes these door systems very difficult to install and maintain, and these systems tend to be expensive and mechanically complex. Some accordion fold door systems are shown in U.S. Pat. Nos. 4,460,030; 3,280,888; and 4,538,661. Cascade door systems are similar to accordion fold systems insofar as they rely upon the use of a door structure comprised of a plurality of panels interconnected into a loop structure. These systems, in addition to being expensive and mechanically complex, tend to occupy relatively large volumes in a stored condition. One such system is shown in U.S. Pat. No. 6,041,843.
In efforts to overcome the problems associated with door systems comprised of linked, accordion fold, or cascade panels, the art has looked to implement hanging panel systems in which a door member is comprised of a plurality of panels which, in a closed condition, cooperate to provide a door structure and which, in an open condition, are disposed in a separated, vertical, side-by-side relationship. While such systems have the potential for allowing for storage of a vertical door in a relatively small compact area, practical implementation of this concept has not heretofore been achieved. For example, U.S. Pat. No. 4,379,478 shows a hanging panel door system which relies upon the use of a pair of relatively complex dual track members for retaining and moving a series of panel members. Furthermore, the panels employed in the system are mechanically complex and include a specific caroming mechanism for assuring their proper motion along the tracks. Another approach implemented in the prior art is depicted in U.S. Pat. No. 3,304,994. This patent shows a hanging panel door system in which a series of cables is employed to move door panels from an overhead storage position to a closed position wherein the panels overlie one another in a shingled relationship. As such, the closed door does not present a uniform, flat surface but rather comprises a plurality of overlapping members. Since the panels do not directly support one another, this system has problems of mechanical stability in addition to being aesthetically unacceptable to many consumers.
As will be detailed hereinbelow, the present invention provides a vertical lift door system which is based upon the use of a plurality of separate panel members which are movable from a hanging, storage position in which the panels are spaced apart in a generally parallel relationship to a closed, use position in which the panels are stacked edge to edge to present a solid, mechanically stable door structure. As will be detailed hereinbelow, the system of the present invention is mechanically simple and does not rely upon the use of complex dual track structures, nor does it require camming members or other such precision mechanical components. The system of the present invention may be implemented in a modular mode wherein individual panels may be configured to particular applications and/or readily replaced. These and other advantages of the invention will be apparent from the drawings, discussion, and description which follow.